1. Field of the Invention
This invention relates to a seat assembly that releasably mounts a seat for both fore and aft travel and pivotal movement on a mobile vehicle such as a tractor and more particularly to an arrangement for limiting stress on both the pivot latch mechanism and the fore-and-aft seat adjuster assembly.
2. Description of the Related Art
Seat supporting assemblies are known which permit the seat first to be slid in a rearward direction on tracks of the fore-and-aft seat adjuster assembly to move the operator away from the steering wheel, control levers and other obstructions, and then unlocked for rotation to a safe and convenient dismount position. This type of seat supporting assembly is disclosed in U.S. Pat. No. 4,014,507, R. Swenson, issued Mar. 29, 1977, and that seat assembly functions well in the use for which it was designed, that is, to assist the operator in safely and conveniently dismounting from a substantially level tractor.
Some purchasers mount attachments on the rear of the tractor, such as a back hoe that has independently operable controls, and the use of such controls requires the seat to be rotated 180.degree. so that the operator will face the rear of the tractor in order to have access to the operating controls for the attachment. The known slidable and pivotable seat arrangements as disclosed in U.S. Pat. No. 4,014,507 have had their intended use expanded by the purchasers to include operation of controls located both at the front and rear of the tractor seat, and this includes fore-and-aft seat movement when the tractor cannot be maintained in a horizontal position.
With rear mounted attachments, the tractor is required to be operated on uneven rough terrain and frequently must be parked with its longitudinal axis at a substantial angle to horizontal. In order to pivot the seat, the operator must first move the seat to its rearmost limit position away from the controls to release the pivot latch mechanism. With the tractor at a substantial angle, one longitudinal direction of seat travel will always be downhill. The fore-and-aft seat adjuster assemblies include internal stops to limit the extent of seat travel in the fore and aft directions. It has been found that heavyweight tractor operators, some weighing 250 pounds or more, plant their feet and push strongly rearward with their legs to cause the seat to travel downhill to a rearmost limit stop position away from whatever controls it faces with such force that prior art pivot latch mechanisms and standard-duty fore-and-aft seat adjuster assemblies do not withstand the stress loading applied by repeated punishing impacts they are subjected to when the seat comes into contact therewith for the purpose of shifting it to an unlatched position. In an attempt to solve the stress failure problem, the tracks and stops of the fore-and-aft seat adjuster assemblies have been made larger and stronger for heavy-duty service. Such heavy-duty seat adjuster assemblies have not solved the problems and significantly increase costs. Further, such expensive, heavy-duty seat adjuster assemblies tend to offer an increase in resistance to fore-and-aft sliding when the tractor is on level terrain which some operators find undesirable. Stress induced failure does not normally develop when the seat is moved to its frontmost limit position toward the controls because the operator is literally pulling the seat toward the frontmost position with his feet and legs and is only able to generate a small fraction of the force that he can generate when pushing rearward.
Making the latch and fore-and-aft seat adjuster assemblies even larger, heavier and stronger would seem to be available as an obvious solution. Unfortunately, the space under the seat wherein the pivot release latch and fore-and-aft seat adjuster assemblies are mounted is severely limited and does not conveniently permit the latch and fore-and-aft seat adjuster assemblies to be made large and heavy enough to withstand the excessive forces that are imposed on them during normal operation. Further, increasing size or reenforcing the latch and the fore-and-aft seat adjuster assemblies results in excessive costs and still does not solve the problem. Therefore, a need exists for a pivotable seat assembly that can use a latch mechanism along with low cost, standard-duty seat adjusters without such components being subject to undue stress and failure.
Another requirement that exists is the need for control switches on the seat assembly which may be used for many purposes such as causing an audible alarm to sound when the seat is rotated to a specific predetermined position. The requirement for switches gives rise to a need for a way to thread conductors up to the seat in a manner that will minimize risk of damage to the conductors during operation of the seat. In the prior art designs, the latch design does not afford a convenient passage through which a conductor can be safely threaded.